The invention relates to an industrial truck having a first and a second controller each of which has an apparatus for a self-diagnosis of sensors and actuators of the controller. Industrial trucks frequently have provided therein several electric controllers to control the transmission unit, hydraulic equipment, and combustion engine, for example.
The electronic control unit of a combustion engine comprises several sensors such as those for the crankshaft speed, the temperature in the intake pipe, the air volume which is drawn in, the pressure on the throttle valve, and the like. The electronic control unit of the combustion engine additionally has a plurality of actuators such as an injection volume regulator, electrovalves to return exhaust gas, and the like. To process the sensor values sensed and energize the actuators, a control unit is provided which processes the sensor signals and outputs setpoints for the control variables to the actuators. The electronic control unit is provided with an apparatus for a self-diagnosis of the system, and signal levels are monitored, for example, to detect a cable break. Also, the sensor values sensed may be compared to modelled sensor values to establish any erroneous function. Erroneous functions or deviations which are recognized are deposited in an error memory of the controller. Individual functions of self-diagnosis may also be initiated by external diagnostic apparatuses which are connected via an appropriate interface. In this case, the erroneous functions deposited in the error memory may be read out and the checking sequences may be released in the controller in question. The diagnostic apparatus evaluates the data read from the error memory and translates them into messages or instructions for the maintenance of the industrial truck.
Now, if a plurality of controllers having different interfaces are provided in industrial trucks it is necessary to provide each controller with a separate diagnostic apparatus which reads data from the error memory and processes them further. Employing a plurality of diagnostic apparatuses has proved to be troublesome and to involve an expenditure. What adds to this is that every diagnostic apparatus is capable of performing a diagnosis only by means of a single controller and will not carry out an overall diagnosis of the industrial truck that takes into account data from more than one controller.
It is the object of the invention to provide an industrial truck which can be diagnosed by means of a diagnostic apparatus in a simple and complete way and processes the diagnostic data in the controllers, thus preventing component overloads.